Subject: Re: separating odd/even harmonics From: Matt Flax <flatmax(at)IEEE.ORG> Date: Fri, 19 Jul 2002 12:09:40 +1000On Thu, Jul 18, 2002 at 11:16:02AM +0200, gia_BERLIN wrote: > Hi all, > > I am in need of Matlab code to separating odd/even harmonics of > quasi-periodic complex sounds (saving them in two Wav files) for use as > experimental stimuli, while preserving the temporal dynamics. Who has some > matlab code for their favorite technique? Hi Chen-Gia, Sorry, I don't have matlab or octave.org code for it, however I would think that it is possible to implement a 'comb filter' which will do exactly what you require. A comb filter is a type of filter which has maxima points seperated by minima points in the frequency spectrum. It looks like this : http://www.audionica.com/Audionicaen/images/comb.gif Where the x label should be 'Frequency' and the y label should be 'Amplitude'. If you design a comb filter which has minima seperated by 2f, where f is the fundamental frequency (of the harmonic spectrum), then you will have a filter which will remove the odd (even) harmonics. Your next step would be to invert the filter in some way such that you would have a comb filter which would have minima where maxima previously were, and vice versa. This would seperate out the even (odd) harmonics. Unfortunatly I don't have time to help you implement this as I am in the middle of writing up my PhD thesis, but next year I should ! good luck Matt > > Thanks, > > Chen-Gia Tsai -- http://mffm.darktech.org WSOLA TimeScale Audio Mod : http://mffmtimescale.sourceforge.net/ FFTw C++ : http://mffmfftwrapper.sourceforge.net/ Vector Bass : http://mffmvectorbass.sourceforge.net/ Multimedia Time Code : http://mffmtimecode.sourceforge.net/
